Identify the correct statements about ECG of a normal human being:
a) P-wave indicates atrial depolarization.
b) QRS complex indicates ventricular repolarization.
c) T-wave represents ventricular repolarization.
d) The interval between S and T represents the atrial systole.

The P-wave in an ECG represents the electrical excitation or depolarization of the atria, which leads to the contraction of both the atria.

The QRS complex represents the depolarization of the ventricles, which initiates the ventricular contraction.

The T-wave represents the return of the ventricles from excited to normal state, which is ventricular repolarization.

The ST segment represents the time when the ventricles are completely depolarized. Atrial systole occurs after the P-wave and before the QRS complex.

Therefore, statements a and c are correct, while b and d are incorrect.

Answer: a and c only